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ED drugs unlikely to increase malignant melanoma risk

Any very small increase in risk with three drugs seems linked to greater sun exposure

Louise Prime

Wednesday, 15 June 2016

Men who take three common erectile dysfunction drugs are unlikely to be increasing their risk of developing malignant melanoma, research suggests. The study*, published in PLOS Medicine, found that any small increase in cancer risk among people using phosphodiesterase type 5 (PDE5) inhibitors seemed to be explained by greater sun exposure.

Reduced expression of PDE5 has been linked to increased growth of melanoma cells in vitro; and earlier studies looking at the risk of malignant melanoma among men taking PDE5 inhibitors have reached conflicting conclusions. To try to clarify whether or not taking PDE5 inhibitors increases the long term risk of developing melanoma, researchers led from the London School of Hygiene & Tropical Medicine carried out a large study in UK men, using anonymised data from the Clinical Research Practice Datalink.

They compared cancer risk in 145,104 men taking sildenafil, tadalafil or vardenafil with that in 560,933 controls. They did find a slightly increased risk of cutaneous melanoma among men taking the drugs – it was 14% higher than in controls – but there were also similarly increased risks of basal cell carcinoma and of solar keratosis, both of which are known to be linked to sun exposure. In fact men taking a PDE5 inhibitor had a higher risk of solar keratosis even before being issued with their first prescription. The risk of colorectal cancer, which is unrelated to sun exposure, was similar in both groups. The study authors said: “There was strong evidence that exposed patients were more likely to have had high sun or UV exposure, even before their first PDE5 inhibitor prescription.”

They concluded: “Our results were not consistent with PDE5 inhibitors being causally associated with melanoma risk, and strongly suggest that observed risk increases are driven by greater sun exposure among patients exposed to a PDE5 inhibitor.”

* Matthews A, Langan SM, Douglas IJ  et al. Phosphodiesterase type 5 inhibitors and risk of malignant melanoma: matched cohort study using primary care data from the UK Clinical Practice Research Datalink. PLoS Med 2016 13(6): e1002037.

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